Show psychology EDUCATION the senses now how we acquire knowledge through them all the knowledge we gain of the outer world we gain by means of the senses no intellectual work such as imagining imag iDing or reasoning can be done till the senses have supplied the materials these materials when reduced to their elements are sensations or sense impressions such stich as those thop of light and color which we receive by means of the eye or sound which wo we have by way of the ear and so on our ideas can never go much beyond our sensations the want of a sense as in the case of one born blind means the depriving of the mind of a whole order of ideas the addition of a new sense if such a thing were possible would enrich our minds by a new kind of knowledge respecting the world A sensation being in its nature an elementary mental phenomenon cannot be defined in terms more simple we can only indicate its meaning by a reference to the nervous processes upon which it is known to depend A sensation is commonly defined as I a dimpled mental state resulting from fro a stimulation or excitation of the outer or peripheral extremely of an in carrying or sensory nerve thus I 1 may bring the nerves of touch say those at the ends of the fingers into contact with a block of ice and immediately 1 I experience the sensation of cold in like manner those nerves when brought into contact with fire will transmit the sensation of heat beat it is necessary to add in this connection n that the sensation is not the immediate consequent of this action in the outer region of the nerve A sensation does not occur at the instant the skin is pricked or when the sound waves im the ear the excitation must be transmitted to the seat of consciousness before a sen aaion is produced thus if by acal accident my hand should come in co contact n with some hot object or an object containing some other peculiar characteristic calculated to excite excia e the nerves of touch there would be no sensation until the excited nerves should carry to the mind the excite ton each individual is endowed with certain senses by means of which the sensations are received which gives us knowledge 0 of the outer world these are what are arc known as the five special senses viz touch sight hearing smell and taste to th these ese some psychologists won would d wish to add the muscular sense of these senses only touch aud and sight will be spoken of here by bj far the most important of these senses in giving knowledge is that of touch as it is through this sense that the first notions of the form and qualities of objects are gained tile the child in the early part of his life cannot judge of the distance nor can he be distinguish any of the qualities of bodies such as their shape size hardness smoothness etc at first he reaches out liis his tiny hand for the moon an cries because lie he cannot get it the rhe object appears to him to be very near and it is only by the bringing into use in later life of the muscular sense that he is able to judge 0 of distance when tile the cb child ild has learned to walk be is beginning to get a notion of space he sees an object and wishes to obtain possession of it but finds that a certain amount of movement is necessary necessary before he is able to realize his wish although the child has the same sense or organs ians and the same fundamental modes of sensibility as the man his bis sensations are more inore crude vague and ill define the repeated I 1 exercise of the senses in connection with attention leads to a gradual dif fern fera of sense impressions and the rendering 0 of them definite in their character to obtain a notion of the size of objects tho the child must learn by a prolonged series of actual act ual experiences to the unpracticed eye of the child every object of whatever form appears as a plane surface the child may see some object say a ball which he be takes in his hand and by the different sensations received by the nerves of touch is able to judge of the form of the object lie ile brings to bear upon the object the organs of vision and he notices the different degrees of light and shade his does not stop here he be examines many objects and notices the light and shade and after repeated experiences of this kind bind lie he learns in a measure to judge of the forms of objects by a reference to the distribution of li light and shade upon the surfaces of the objects but after he be has arrived at this stage t of perfection in his big observation lie he must yet rely upon the sense of touch to give him bi lm accurate knowledge respecting the roughness hardness or weight of objects welch in explaining ning how the hand touches the eye says the qualities of objects as revealed to touch through resistance are solidity shape size hardness smoothness etc etc now these qualities of matter are made known to us directly through the perceptions of touch only the eye recognizes directly the modifications of light alone it perceives immediately the colors including U cl 0 what are called light and shade light and shade are to the eye only the visible signs of solidity extension and shape the eye does not perceive these qualities but infers them from the varieties of light and shade which their surfaces present this may be shown in several ways when whan the eye cannot destina distinguish g aish the light and shade of an object because of distance its special shape cannot be determined and it becomes only a dim visual obstruction second Is a painter may so represent light and shade on a plane surface that the eye accepts them as ai indicating di actual solid 0 0 an fig figure ure once visiting a church I 1 observed that its walls were ornamented with beautiful conventional figures that to the sense of sight stood out as solid realities I 1 could not distinguish them from actual shapes except by passing the hand along the wall on which they were painted and finding it a plane surface now arises a question if the eye cannot directly perceived a solid body but only the arrangement of light and shade that lie upon its surfaces in what way does the mind learn that these are the signs of extension in three directions and constitutes utes a solid there is but one answer to this question the hand which is earlier in action teaches the eye by countless instances that the adjustment of light and shade it perceives signi signifies fles shape and when the eye is thus taught every sight per caption is attended by a judgement jud gement or inference which is so and rapid as to elude our consciousness in fact the alie perception of light and shade and the inference of shape are arc so welded together by habit that the intellect accepts them as a single act U UC C |